Muscle Fatigue in the Three Heads of Triceps Brachii During Intensity and Speed Variations of Triceps Push-Down Exercise

The objective of this study was to investigate the effects of changes in exercise intensity and speed on the three heads of the triceps brachii (TB) during triceps push-down exercise until task failure. Twenty-five subjects performed triceps push-down exercise at three different intensities (30, 45, and 60% 1RM) and speeds (slow, medium, and fast) until failure, and surface electromyography (sEMG) signals were recorded from the lateral, long and medial heads of the TB. The endurance time (ET), number of repetitions (NR) and rate of fatigue (ROF) were analyzed. Subsequently, the root-mean-square (RMS), mean power frequency (MPF) and median frequency (MDF) under no-fatigue (NF) and fatigue (Fa) conditions were statistically compared. The findings reveal that ROF increases with increase in the intensity and speed, and the opposite were obtained for the ET. The ROF in the three heads were comparable for all intensities and speeds. The ROF showed a significant difference (P < 0.05) among the three intensities and speeds for all heads. The three heads showed significantly different (P < 0.05) MPF and MDF values for all the performed exercises under both conditions, whereas the RMS values were significantly different only under Fa conditions. The current observations suggest that exercise intensity and speed affect the ROF while changes in intensity do not affect the MPF and MDF under Fa conditions. The behavior of the spectral parameters indicate that the three heads do not work in unison under any of the conditions. Changes in the speed of triceps push-down exercise affects the lateral and long heads, but changes in the exercise intensity affected the attributes of all heads to a greater extent.

Reliability of Electromyographic Assessment of Biceps Brachii and Triceps Brachii in Cricketers

Objective

The purpose of this study is to determine the intraexaminer and interexaminer reliability of electromyographic assessment of biceps brachii (BB) and triceps brachii (TB) muscles in cricketers.

Methods

Sixteen healthy male cricketers (ages 14-35 years) recruited from Jamia Millia Islamia, New Delhi, India were tested on 2 occasions that were held 1 week apart. On the first occasion, only examiner 1 performed the testing; on the second occasion, examiner 1, examiner 2, and examiner 3 all performed testing. While testing for surface electromyography (sEMG) activity of BB and TB muscles, participants were asked to produce maximal voluntary isometric contraction (MVIC), which was to be held for 5 seconds against the resistance provided by an examiner. Participants performed 3 MVICs per muscle per examiner, with a rest interval of 3 minutes between consecutive contractions. Intraclass correlation coefficient, standard error of measurement, and minimum detectable change were calculated to determine the reliability of repeated sEMG measurements.

Results

Nonsignificant differences were observed for the 2 trials completed by examiner 1 (paired t test) and testing done by all 3 examiners (repeated measures analysis of variance) at P < .05 for both BB and TB. Intraclass correlation coefficient values ranged from .84 to .86 for BB and .89 to .98 for TB. Standard error of measurement (minimum detectable change) was .052 (.144) mV and .041 (.114) mV for BB intraexaminer and interexaminer reliability testing, respectively, and .018 (.051) mV and .043 (.119) mV for TB intraexaminer and interexaminer reliability testing. Ninety-five percent of the mean differences between almost all of the repeated measurements were found to lie within the agreement intervals estimated by Bland-Altman plots.

Conclusion

This preliminary study suggests that sEMG is a reliable tool with excellent intraexaminer and interexaminer reliability for assessing the activity of BB and TB muscles in male cricketers. These findings suggest that sEMG can be used to assess MVIC activity of these muscles in clinical settings, as well as in research area.